1. Field of the Invention
The invention relates to a selector valve and a cooling system and, more particularly, to a selector valve that switches a flow passage of fluid and a cooling system that includes the selector valve.
2. Description of Related Art
In recent years, hybrid vehicles, fuel cell vehicles, electric vehicles, and the like, that travel with the use of driving force of a motor become a focus of attention as one of measures against environmental issues. In such vehicles, electrical devices, such as a motor, a generator, an inverter, a converter and a battery, exchange electric power to generate heat. Therefore, these electrical devices need to be cooled.
Japanese Patent Application Publication No. 2000-73763 (JP 2000-73763 A) describes a hybrid vehicle cooling system that includes a first cooling circuit that cools an engine cylinder head and a driving motor selectively or simultaneously, a second cooling circuit that cools an engine cylinder block and a third cooling circuit that cools a power control unit that executes drive control over the driving motor.
In the cooling system described in JP 2000-73763 A, as in the case of a normal vehicle that cools only an engine, a system that circulates coolant between a heat generating element and a radiator is used to cool an electrical component. In such a system, a radiator for cooling an electrical component is required to be additionally provided, so there is inconvenience that vehicle mountability is low.
Then, there has been suggested a technique that utilizes a vapor compression refrigeration cycle, which is used as a vehicle air conditioner, to cool a heat generating element. For example, Japanese Patent Application Publication No. 2005-90862 (JP 2005-90862 A) describes a cooling system in which a heat generating element cooling unit for cooling a heat generating element is provided in a bypass line that bypasses the decompressor, evaporator and compressor of an air-conditioning refrigeration cycle. Japanese Patent Application Publication No. 2007-69733 (JP 2007-69733 A) describes a system in which a heat exchanger that exchanges heat with air-conditioning air and a heat exchanger that exchanges heat with a heat generating element are arranged in parallel with each other in a refrigerant line routed from an expansion valve to a compressor and refrigerant for an air conditioner is utilized to cool the heat generating element.
On the other hand, in relation to a selector valve used to switch an operation mode of an air-conditioning system, Japanese Patent Application Publication No. 6-194007 (JP 6-194007 A) describes a configuration that a rotor having radial holes and inserted in a spool is rotated by a motor to sequentially open or close holes of the spool to thereby switch a flow passage.
In a system that is able to switch a flow passage through which fluid passes, when a plurality of control valves for switching the flow passage, the configuration of the system is complex, and there is inconvenience that the size and cost of the system increase. The selector valve described in JP 6-194007 A is formed of an integrated valve that is able to switch a plurality of valves with the use of a single drive unit. By so doing, it is intended to reduce the size and cost of the system.
However, in the selector valve described in JP 6-194007 A, both low-temperature fluid before passing through a compressor and high-temperature fluid after passing through the compressor flow through the integrated valve structure. When fluids in different temperature ranges respectively flow through different flow passages in the integrated valve structure, heat transfers from the high-temperature fluid to the low-temperature fluid. Therefore, the performance of the air-conditioning system is decreased, so there is inconvenience that power consumption is increased.